The present invention relates to ophthalmic lenses. More particularly, the invention relates to multifocal ophthalmic lenses for use in or on the eye, such as intraocular lenses, contact lenses, corneal implant lenses and the like.
The general construction of a multifocal ophthalmic lens is known in the art. For example, Portney U.S. Pat. No. 5,225,858, which is incorporated herein by reference, discloses a multifocal ophthalmic lens including a central zone circumscribed by multiple concentric, annular zones. This patent discloses multifocal lenses having good image quality and light intensity for near objects. The multifocal lens of this patent includes zones for near vision correction in which the vision correction power substantially constant throughout.
Although multifocal lenses of this type provide very effective vision correction, further enhancements would be advantageous.
For example, experience with multifocal lenses as described above has identified two general types of night time visual symptoms referred to as "glare or flare" and "halos". The "glare or flare" symptom manifests itself as radial lines radiating from distant small bright objects at night. The "halos" symptom generally manifest itself as diffuse shadows surrounding distant small bright objects, again noticed at night. These visual symptoms are likely caused by out of focus light passing through the near zone or zones of the lenses.